Effect Of Ce Addition Research Articles

Effects of Ce additions on microstructure and properties of Cu-15Cr in situ composite

Cu-15Cr and Cu-15Cr-0.05Ce in situ composites are fabricated by the cast-intermediate heat treatment (IHT)-deformation technology process. The microstructure, mechanical property, conductivity, and the wear resistance were studied by Optical microscope, Scanning electronic microscope, tensile-testing machine and Pin-on-bar reciprocating wear tester, respectively. The results show that the trace addition of Ce elements can refine the primary phase dendrites and deformed Cr fibers, increasing the intensity significantly but slightly improving the conductivity. On this basis, the mechanism of strength and conductivity is discussed. Compared to the Cu-15Cr alloy, the hardness and wear resistance of the Cu-15Cr-Ce alloy are improved due to the addition of Ce to refine the Cr fibers.

Effect of Ce Addition on Microstructure, Thermal Conductivity, and Mechanical Properties of As-Cast and As-Extruded Mg-3Sn Alloys.

In the present research, the impacts of Ce additions at various concentrations (0, 1.0, 3.4, and 4.0 wt.%) on the evolution of the microstructure, mechanical properties, and thermal conductivity of as-cast and as-extruded Mg-3Sn alloys were investigated. The findings demonstrate that adding Ce caused the creation of a new ternary MgSnCe phase in the magnesium matrix. Some new Mg17Ce2 phases are generated in the microstructure when Ce levels reach 4%. The thermal conductivity of the Mg-3Sn alloy is significantly improved due to Ce addition, and the Mg-3Sn-3.4Ce alloy exhibits the highest thermal conductivity, up to 133.8 W/(m·K) at 298 K. After extrusion, both the thermal conductivity and mechanical properties are further improved. The thermal conductivity perpendicular to the extrusion direction of Mg-3Sn-3.4Ce alloy could achieve 136.28 W/(m·K), and the tensile and yield strengths reach 264.3 MPa and 227.2 MPa, with an elongation of 7.9%. Adding Ce decreases the dissolved Sn atoms and breaks the eutectic α-Mg and Mg2Sn network organization, leading to a considerable increase in the thermal conductivity of as-cast Mg-3Sn alloys. Weakening the deformed grain texture contributed to the further enhancement of the thermal conductivity after extrusion.

Effects of Ce addition on inclusion modification in martensitic stainless steel

The control of inclusion features, i.e., chemical composition, distribution, quantity, and size, is in high demand for stainless steels to achieve good surface quality, pitting corrosion resistance, and mechanical properties. In this paper, the effects of rare earth (RE) modification on the inclusions of martensitic stainless steel were explored. Martensitic stainless steels with various contents of Ce were prepared, and the inclusions in the cast billets were characterized by field emission scanning electron microscopy (FE-SEM) and an automatic analysis system for nonmetallic inclusions in steels (OTS). The effect of Ce on the modification of nonmetallic inclusions during solidification was explored with thermodynamic calculations. The results showed that the addition of Ce modified the oxygen and sulfur inclusions by transforming them from irregular elongated inclusions to nearly spherical RE composite inclusions. Compared with those in basic martensitic stainless steel, nine types of RE inclusions were found in the presence of Ce. As the Ce content increased from 0.048 wt% to 0.092 wt%, the CeAlO3 content decreased, whereas the Ce2O2S content increased. Moreover, there were 80% fewer inclusions than in the basic martensitic stainless steel.

Effect of Ce addition on the nucleation and growth of austenite in ultra-high-strength steel

The effect of varying rare earth element cerium (Ce) contents (0∼0.0792 wt%) on the austenite grain size of ultra-high-strength engineering steel has been studied under different austenitization conditions (holding time of 5∼360 min at temperatures ranging from 900 °C to 1200 °C). Results show that the addition of Ce can refine grains, and the refining effect becomes more pronounced as the Ce content increases. The inhibition of austenite grain growth by fine Ce-containing inclusions during the holding process has been observed through laser scanning confocal microscopy (LSCM) and field-emission scanning electron microscope (FE-SEM) equipped with an energy dispersive spectrometer (EDS), and the pinning effect of Ce-containing inclusions on the austenite grain boundaries is the primary factor for the refinement of austenite grains. Besides, theoretical calculations have shown that the lattice misfits between the (100) plane of CeP and the (111) plane of the γ-phase is 7.83%, indicating that CeP could serve as a heterogeneous nucleation core for the γ-phase and was moderately effective. Furthermore, the uniformization effect of Ce on the grains is more prominent than the refining effect at the holding temperatures of 1000 °C and 1200 °C.

Effect of Ce Addition on Inclusions and Primary Carbide Network in AISI 440C Bearing Steel

The effects of Ce on inclusions and the primary carbide network of AISI 440C bearing steel are experimentally and theoretically investigated. Adding Ce improves the cleanliness and refinement of primary carbide networks in AISI 440C bearing steel ingots. The addition of Ce substantially reduces the contents of total oxygen (T.O) and S in the steel, and MnS and Al2O3 inclusions are modified into finer Ce‐containing inclusions (Ce2O2S and Ce2O3). When Ce is added, the average equivalent diameter of the inclusions decreases from 1.82 to 1.33 μm, and the number of inclusions per unit area (mm2) increases from 59 to 105. Moreover, the addition of Ce reduces the secondary dendrite spacing from 33.82 to 24.2 μm, and the proportion of primary carbide is reduced from 22.08% to 11.17%. The 2D lattice disregistry theory confirms that Ce2O2S and Ce2O3 inclusions can be utilized as effective heterogeneous nucleation cores for γ‐Fe, thus refining the solidification microstructure and also the primary carbide. This study provides theoretical guidelines for the fabrication of domestic AISI 440C bearing steel ingots.

A new insight into the mechanism of Ce enhancing high temperature oxidation resistance of hot-formed steel

In this paper, the effect of Ce addition on high temperature oxidation behavior of hot-formed steel was studied by high temperature oxidation experiment. The structure and phase composition of surface oxide layer of specimens with different Ce content were systematically analyzed by SEM, EDS, XPS. The results showed that the addition of Ce promoted the formation of a dense oxide layer during the initial oxidation stage, and effectively weaken the oxidation degree of the steel surface. Meanwhile, the Ce2O3 particles segregation in Si–Cr rich phase reduced the concentration of vacancy defects in oxide layer and enhanced the adhesion between oxide layer and substrate. After Ce addition, the surface oxidation resistance of hot-formed steel is significantly improved.

Effects of Ce addition on mechanical properties and thermal expansion behavior of Fe-36Ni Invar alloy

To pursue superior yield strength and low thermal expansion characteristic of Fe-36Ni Invar alloy, Fe-36Ni Invar alloys containing various cerium (Ce) contents (0 wt%, 0.0050 wt%, 0.0170 wt%, and 0.0360 wt%) were prepared by vacuum induction melting, followed by the heat treatment process. With increasing Ce content, the evolution of the second-phase particles followed the sequence: MnO-MnS (0% Ce) → MnO-MnS + Ce2O3 (0.0050% Ce) → Ce2O3 + Ce2O2S (0.0170% Ce) → Ce2O3 + Ce2O2S + Ni5Ce (0.0360% Ce). The results indicated that the grain size and the fraction of annealing twins (fAT) were fairly sensitive to the Ce content. The smallest average grain size (d¯) and the highest fAT were obtained by adding 0.0170% Ce. The small addition of Ce was beneficial to the improvement of strength and low thermal expansion behavior. In particular, 0.0170% Ce alloy achieved the optimal combination properties. However, the excessive addition of Ce (0.0360%) induced a sharp decrease in mechanical performance and an undesirable increase in the coefficient of thermal expansion (CTE). The Ni5Ce phase was unfavorable to the enhancement of mechanical properties and low thermal expansion behavior. Last but not least, 0.0170 wt% Ce content was advised for Fe-36Ni Invar alloy by considering the balance of strength and thermal expansion behavior.

Ce effects on dynamic recrystallization and microstructure of the copper alloy under hot deformation behavior with different strain rate

The Cu–Ni–Sn–Ti–Cr and Cu–Ni–Sn–Ti–Cr–Ce alloys were compressed at 500–900 °C with 0.001–10 s−1 strain rates using the Gleeble 1500 deformation simulator. The effects of Ce addition on the microstructure and recrystallized grains of Cu–Ni–Sn–Ti–Cr alloy were investigated using EBSD and TEM. A constitutive equation was established to calculate the activation energy for the alloy hot deformation, and the optimal processing parameters were obtained. The corresponding texture of the Cu–Ni–Sn–Ti–Cr–Ce alloy deformed at 800 °C with 0.01 s−1, 0.1 s−1 and 1 s−1 strain rates is the {112}<100> Copper, {001}<111> Cubic and {011}<100> Goss texture. The texture of the Cu–Ni–Sn–Ti–Cr alloy deformed at 800 °C and 0.1 s−1 strain rate is the {011}<100> Goss texture. The strain rate and Ce addition can change the alloy texture. The precipitation phase in Cu–Ni–Sn–Ti–Cr (-Ce) alloy is mainly CuNi2Ti phase, and the addition of Ce can promote the precipitation of fine nanoscale precipitation phase in the alloy. Moreover, the addition of Ce can promote the dynamic recrystallization of the alloy, but the dynamic recrystallization of the alloy is suppressed with the increase of the hot deformation rate at the heat deformation temperature of 800 °C.

Effect of Ce addition on microstructure, thermal and mechanical properties of Al-Si alloys

Effect of Ce addition on microstructure, thermal and mechanical properties of Al-Si alloys

Excellent catalytic oxidation performance on toluene over Pt supported on CeaTiOx with hierarchical tubular-like structures: Effects of Ce addition in CeaTiOx on activity of Pt/CeaTiOx

Volatile organic compounds (VOCs) have become a type of tricky gaseous contaminant in modern industry. Catalytic oxidation is believed to be an effective way to remove VOCs in low concentration. A series of Pt-supported CeaTiOx with hierarchical tubular-like structure assembled by flakes was prepared and applied in catalytic toluene oxidation. Pt/Ce0.15TiOx with low Ce amount showed enhanced catalytic performance (T50 = 147 ℃ and T90 = 162 ℃) and good durability in long-term use, recycling use and water resistance. Various characterizations were used to investigate the influence of Ce addition on activity. In situ DRIFTS of toluene oxidation disclosed that Ce addition boosted the oxidation process at lower temperature where surface adsorb oxygen plays a vital role. The appropriate Ce addition was proved to be benefit for Pt dispersion, formation of more Pt0 species that were derived from metal-support interaction (MSI) between Pt and Ce0.15TiOx, which comprehensively attributed to its excellent performance.

Effect of cerium on microstructure, texture and properties of ultrahigh-purity copper

The effects of Ce addition (310 ppm and 1500 ppm) on the microstructure, texture and properties of ultrahigh-purity copper (99.99999%) were systematically studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD) analyses, combined with the microhardness and conductivity tests. Regarding the microstructure of the as-cast and as-extruded samples, the addition of Ce refines the grain size of the ultrahigh-purity copper and the refinement effect of 310Ce alloy is greater than that of 1500Ce alloy. This is due to the stronger component supercooling and the accelerated recrystallization caused by lower Ce content. In addition, Ce can react with Cu to form the Cu–Ce eutectic phases, which are deformable during the hot deformation. Furthermore, the added Ce can weaken the texture, showing a variation of brass recrystallization (BR), rotated cube, copper and S texture components, which depends on the recrystallization, the particle stimulated nucleation (PSN) as well as the stacking fault energy (SFE). Most remarkably, the introduction of Ce enhances the hardness of the ultrahigh-purity copper without obviously reducing its conductivity. The major {111} orientations and the stress distributions are responsible for such a superior conductivity of the Ce-containing alloys.

The effect of Ce addition on purification and inclusion modification of CoCrFeNiMn high entropy alloy

This study focuses on purification and inclusion modification mechanism of equiatomic CoCrFeNiMn high entropy alloys with addition of various cerium (within the range of 0–0.0445 %) smelted by Vacuum Arc Melting (VAM), It was found that there are three types of inclusions in CoCrFeNiMn alloys: Mn(S, Se), AB2O4 spinel type, mixed type (Mn(S, Se) wraps AB2O4), and the average size of the three types of inclusions are 1.1 µm, 5.6 µm, and 4.8 µm, respectively. The addition of cerium can significantly reduce the oxygen content, as well as the sulfur content and selenium content are declined, the inclusions are refined and spheroidized simultaneously. The oxygen content, sulfur content and selenium content were reduced from 150 ppm, 46 ppm, and 105 ppm to 5–7 ppm, 22 ppm, and 80 ppm, respectively. When the cerium content is 0.0012 %, some of the inclusions are modified into three types of inclusions: Mn(S, Se) + Ce2O3, Mn(S, Se) + CeCrO3 and Mn(S, Se) + Ce2O3 + CeCrO3, while the average size of some unmodified AB2O4 spinel inclusions was reduced to 3.1 µm, and the average size of mixed inclusions was dropped to 2.6 µm. When the cerium content is 0.019 %, the inclusions in the alloy are completely modified into Ce2O2(S, Se) + Ce2(S, Se)3. Furthermore, the number density and area fraction of the inclusions are descended from 216.92 mm−2 and 0.1150 % of no cerium alloys to 121.64 mm−2 and 0.0602 %, the inclusions are well spheroidized, and the average size of cerium inclusions is 2.2 µm. Finally, the mechanism on the modification by cerium was discussed based on the composition evolution of inclusion during solidification with Factsage calculation and experimental results. The compositions of inclusions were also analyzed based on the inclusion evolution model.

Effects of Ce addition on the oxidation behavior of Ni-28W-6Cr superalloy

The oxidation behavior of Ni-28W-6Cr-(0–0.190 wt%)Ce alloys at 850 °C was investigated. The addition of Ce significantly decreases the oxidation rate of the alloys and the thickness of the inner oxide scale when the Ce content is below 0.023 wt%. Then the decrease slows down when the Ce content reaches 0.190 wt% due to the consumption of Ce in the γ matrix caused by the formation of Ni-Ce phase. Ce is solid-soluted in the inner oxide NiWO4 and replaces the Ni2+ by Ce with the valence of + 3 and + 4, therefore, the formation of oxygen vacancies and oxygen diffusion are inhibited.

Preparation of Cex-Mn0.8Fe0.2O2 Catalysts and Its Anti-Sulfur Denitration Performance

In order to meet the industrial denitrification demands, inexpensive ferrous metals Mn and Fe have been chosen as the raw materials for the catalysts of CO-SCR, and the anti-sulfur denitrification performance of ferromanganese catalysts can be greatly enhanced by Ce doping. In this study, Cex-Mn0.8Fe0.2O2 catalysts were prepared by co-precipitation, and the effects of Ce addition on the structure and morphology of prepared catalysts and their anti-sulfur denitration performance were investigated with X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results showed that the Cex-Mn0.8Fe0.2O2 catalysts consisted of nanoparticles sized 20–100 nm. Specifically, the Ce0.2-Mn0.8Fe0.2O2 catalyst had more active sites and the best anti-sulfur denitration performance, with a denitration rate of 90.36% at 350 °C, while the denitrification performance of the Mn0.8Fe0.2O2 catalyst was only 85%. Furthermore, the denitrification rate of the catalyst was maintained above 80% when the CO:NO:SO2 ratio was 3:1:1 for 4 h at 350 °C.

Effect of Ce addition on microstructure and hardness of (Ni2CoFe)86Ti8Al6 high entropy alloy

The effects of different Ce contents on the microstructure and hardness of (Ni2CoFe)86-xTi8Al6Cex (x = 0, 0.1, 0.3, 0.5, 0.7, 1.0 molar ratio) high entropy alloys were systematically studied. The results show that the addition of Ce promotes the precipitation of new FCC and BCC phases. The precipitates were promoted by Ce, and the grains and structures were refined by Ce. With the gradual increase of Ce content, the hardness gradually increases. The microhardness (HV) of (Ni2CoFe)85Ti8Al6Ce HEA is 458.6. The increase of precipitate volume fraction and fine grain strengthening are the main reasons for the increase of hardness.

Effect of Ce addition on hot corrosion behaviours of a cast γ′-strengthened Co–Al–W–Mo–Ta–B alloy at 800 ​°C

Hot corrosion behaviours of a novel Co–9Al-4.5W-4.5Mo–2Ta-0.02B alloy doped with 0.01, 0.05, 0.1 and 0.2 ​at% Ce exposed at 800 ​°C in a solution of 75%Na2SO4/25%NaCl were investigated. The alloys comprised a coherent γ-CoSS/γ′-Co3(Al, W) microstructure (0.01Ce and 0.05Ce alloys) and κ-Co3(W, Mo) precipitates (0.1Ce and 0.2Ce alloys) at grain boundaries. Hot corrosion kinetics curves demonstrated the parabolic time dependency profile with two stages: the first parabolic stage is within the beginning ∼50 ​h corrosion and follows by the second parabolic stage. With an increasing nominal Ce content the weight gain of the alloy significantly decreased from approximately 70.1 ​mg ​cm−2 (0.01Ce) to 40.8 ​mg ​cm−2 (0.2Ce) when exposed for 100 ​h. A two-layer corrosion scale formed, and the scale was composed of an outer layer of Co3O4 oxide with spinel compounds of CoAl2O4, CoWO4and CoSO4, and an inner γ/needle-like Co3W/sulphide layer adhered to the substrate. Heavy spallation of the corrosion scale occurred in the 0.01Ce∼0.1Ce alloys, however, spallation was slight in the 0.2Ce alloy. The excellent corrosion resistance of the 0.2Ce alloy could be attributed mainly to the formation of continuous Al2O3 lines in the corrosion scale, as well as the prolongation of the incubation period of the corrosion product spallation.

Effect of Ce Addition on the Thermal Conductivity and Mechanical Properties of Al-7Si-0.6Fe-0.5Zn Cast Alloy Treated by B/La/Sr Modification

Effect of Ce Addition on the Thermal Conductivity and Mechanical Properties of Al-7Si-0.6Fe-0.5Zn Cast Alloy Treated by B/La/Sr Modification

Effect of Ce addition on the high‐temperature oxidation resistance of Mg–Gd alloys

AbstractIn the present study, the oxidation resistance of magnesium alloyed with Gd and Ce was investigated. The high‐temperature oxidation resistance of Mg–3.5Gd–xCe (x = 0, 0.2, 0.4, 0.7 and 1.0 wt%) alloys was evaluated at temperatures between 550°C and 650°C. Results indicate that adding less than 0.7 wt% Ce resulted in high oxidation resistance, whereas the Ce addition exceeding 0.7 wt% deteriorated the oxidation resistance. The high oxidation resistance phenomenon is attributed to the formation of compact oxide films primarily composed of MgO, Gd2O3, and a small amount of CeO2 on the surface of Mg–3.5Gd–0.2Ce and Mg–3.5Gd–0.4Ce alloys. These compact oxide films can prevent the matrix from experiencing further oxidation. The deteriorated oxidation resistances of Mg–3.5Gd–0.7Ce and Mg–3.5Gd–1Ce alloys were found to be due to the severe internal oxidation caused by the distributed Mg12Ce phases along the grain boundaries.

Effect of Ce on microstructures, carbides and mechanical properties in simulated coarse-grained heat-affected zone of 800-MPa high-strength low-alloy steel

The application of oxide metallurgy technology to induce the formation of acicular ferrite in coarse-grained heat-affected zone (CGHAZ) to improve the welding performance of steel is a research hotspot in recent years. However, the enhancement mechanism of mechanical properties after Ce addition and the behavior of microstructures in CGHAZ of 800-MPa high-strength low-alloy (HSLA) steel are rarely reported. In the present study, the effect of Ce addition on the welding performance of 800-MPa HSLA steel was investigated by analyzing the microstructures, carbides and mechanical properties in the simulated CGHAZ. The results indicated that after the welding thermal cycle, the decrease in toughness in the CGHAZ was mainly caused by the significant decrease in the crack propagation energy. Compared to the Ce-free steel, Ce addition improved the toughness of the base metal and CGHAZ by increasing the crack propagation energy. With the same heat input, the CGHAZ strength of the Ce-containing steel was higher than that of the Ce-free steel. During the welding thermal cycle, the Nb and Ti carbonitrides greatly affected the grain growth in the CGHAZ. Ce addition significantly refined these carbonitrides, providing a stronger pinning pressure to inhibit austenite grain growth in the CGHAZ. Ce addition also refined the austenite grains and increased the proportion of high-angle boundaries in the CGHAZ, increasing the impact absorb energy and decreasing the strength loss of the CGHAZ, essentially improving the welding performance of the HSLA steel. These results are helpful for clarify the mechanism by which Ce improved the welding performance of the 800-MPa HSLA steel.

Effect of Ce on Microstructure and Mechanical Properties of AZ91 Magnesium Alloy

In this paper, gravity casting experiments were used to prepare AZ91-xCe alloys, and the effects of Ce addition on the mechanical properties and structure of the AZ91-xCe alloy were analyzed. X-ray diffractometry and metallurgical microscopy were used to characterize the phase composition and microstructure of the experimental alloy, and the strength and hardness of the alloy were tested and analyzed. Results show that the addition of a small amount of Ce generates a high melting point, thermally stable A14Ce, and reduces the porosity of the alloy. The tensile strength and yield strength of the AZ91-xCe alloy have been significantly improved under joint strengthening of multiple mechanisms of fine-grain strengthening, precipitation strengthening, and solid solution strengthening. By comparing and observing the mechanical properties and microstructures of alloys with different Ce concentrations, it was concluded that at a Ce content of 0.5%, the overall performance of the alloy is optimal. Compared to the AZ91 alloy, the tensile strength was increased by 29% and the yield strength was increased by 34%.